Organic electroluminescent materials and devices

ABSTRACT

Novel host compounds containing indolo[3,2,1-jk]carbazole moiety are disclosed. These compounds are useful in phosphorescent OLEDs and particularly as hosts and/or electron-blocking layer materials.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a non-provisional application claiming priority under 35 U.S.C. § 119(e) to U.S. Provisional Application Ser. No. 61/974,057, filed Apr. 2, 2014, the entire contents of which is incorporated herein by reference.

PARTIES TO A JOINT RESEARCH AGREEMENT

The claimed invention was made by, on behalf of, and/or in connection with one or more of the following parties to a joint university corporation research agreement: The Regents of the University of Michigan, Princeton University, University of Southern California, and Universal Display Corporation. The agreement was in effect on and before the date the claimed invention was made, and the claimed invention was made as a result of activities undertaken within the scope of the agreement.

FIELD OF THE INVENTION

The present invention relates to organic light emitting devices (OLEDs), and to organic materials used in such devices. More specifically, the present invention relates to novel organic materials for use as support layers in OLEDs, in particular as hosts and electron-blocking layer materials, but not limited as such. The materials are based on indolo[3,2,1-jk]carbazole moiety. The compounds are expected to improve phosphorescent OLED performance.

BACKGROUND

Opto-electronic devices that make use of organic materials are becoming increasingly desirable for a number of reasons. Many of the materials used to make such devices are relatively inexpensive, so organic opto-electronic devices have the potential for cost advantages over inorganic devices. In addition, the inherent properties of organic materials, such as their flexibility, may make them well suited for particular applications such as fabrication on a flexible substrate. Examples of organic opto-electronic devices include organic light emitting devices (OLEDs), organic phototransistors, organic photovoltaic cells, and organic photodetectors. For OLEDs, the organic materials may have performance advantages over conventional materials. For example, the wavelength at which an organic emissive layer emits light may generally be readily tuned with appropriate dopants.

OLEDs make use of thin organic films that emit light when voltage is applied across the device. OLEDs are becoming an increasingly interesting technology for use in applications such as flat panel displays, illumination, and backlighting. Several OLED materials and configurations are described in U.S. Pat. Nos. 5,844,363, 6,303,238, and 5,707,745, which are incorporated herein by reference in their entirety.

One application for phosphorescent emissive molecules is a full color display. Industry standards for such a display call for pixels adapted to emit particular colors, referred to as “saturated” colors. In particular, these standards call for saturated red, green, and blue pixels. Color may be measured using CIE coordinates, which are well known to the art.

One example of a green emissive molecule is tris(2-phenylpyridine) iridium, denoted Ir(ppy)₃, which has the following structure:

In this, and later figures herein, we depict the dative bond from nitrogen to metal (here, Ir) as a straight line.

As used herein, the term “organic” includes polymeric materials as well as small molecule organic materials that may be used to fabricate organic opto-electronic devices. “Small molecule” refers to any organic material that is not a polymer, and “small molecules” may actually be quite large. Small molecules may include repeat units in some circumstances. For example, using a long chain alkyl group as a substituent does not remove a molecule from the “small molecule” class. Small molecules may also be incorporated into polymers, for example as a pendent group on a polymer backbone or as a part of the backbone. Small molecules may also serve as the core moiety of a dendrimer, which consists of a series of chemical shells built on the core moiety. The core moiety of a dendrimer may be a fluorescent or phosphorescent small molecule emitter. A dendrimer may be a “small molecule,” and it is believed that all dendrimers currently used in the field of OLEDs are small molecules.

As used herein, “top” means furthest away from the substrate, while “bottom” means closest to the substrate. Where a first layer is described as “disposed over” a second layer, the first layer is disposed further away from substrate. There may be other layers between the first and second layer, unless it is specified that the first layer is “in contact with” the second layer. For example, a cathode may be described as “disposed over” an anode, even though there are various organic layers in between.

As used herein, “solution processible” means capable of being dissolved, dispersed, or transported in and/or deposited from a liquid medium, either in solution or suspension form.

A ligand may be referred to as “photoactive” when it is believed that the ligand directly contributes to the photoactive properties of an emissive material. A ligand may be referred to as “ancillary” when it is believed that the ligand does not contribute to the photoactive properties of an emissive material, although an ancillary ligand may alter the properties of a photoactive ligand.

As used herein, and as would be generally understood by one skilled in the art, a first “Highest Occupied Molecular Orbital” (HOMO) or “Lowest Unoccupied Molecular Orbital” (LUMO) energy level is “greater than” or “higher than” a second HOMO or LUMO energy level if the first energy level is closer to the vacuum energy level. Since ionization potentials (IP) are measured as a negative energy relative to a vacuum level, a higher HOMO energy level corresponds to an IP having a smaller absolute value (an IP that is less negative). Similarly, a higher LUMO energy level corresponds to an electron affinity (EA) having a smaller absolute value (an EA that is less negative). On a conventional energy level diagram, with the vacuum level at the top, the LUMO energy level of a material is higher than the HOMO energy level of the same material. A “higher” HOMO or LUMO energy level appears closer to the top of such a diagram than a “lower” HOMO or LUMO energy level.

As used herein, and as would be generally understood by one skilled in the art, a first work function is “greater than” or “higher than” a second work function if the first work function has a higher absolute value. Because work functions are generally measured as negative numbers relative to vacuum level, this means that a “higher” work function is more negative. On a conventional energy level diagram, with the vacuum level at the top, a “higher” work function is illustrated as further away from the vacuum level in the downward direction. Thus, the definitions of HOMO and LUMO energy levels follow a different convention than work functions.

More details on OLEDs, and the definitions described above, can be found in U.S. Pat. No. 7,279,704, which is incorporated herein by reference in its entirety.

SUMMARY OF THE INVENTION

According to an embodiment, a compound is provided that has the structure according to a formula G¹-G²-G³-G⁴-G⁵, Formula I;

wherein G¹ has the structure:

-   -   wherein R¹ and R³ each independently represent mono, di, tri, or         tetra substitutions, or no substitution,     -   wherein R² represents mono, di, or tri substitutions, or no         substitution,     -   wherein R¹, R², and R³ are each independently selected from the         group consisting of hydrogen, deuterium, halogen, alkyl,         cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino,         silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl,         heteroaryl, acyl, carbonyl, carboxylic acid, ester, nitrile,         isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and         combinations thereof;

wherein G² and G⁴ are each independently selected from the group consisting of a direct bond, an aryl group having from 6-30 carbon atoms, a heteroaryl group having from 3-30 carbon atoms, and combinations thereof,

-   -   wherein the aryl group and the heteroaryl group are optionally         further substituted with one or more groups selected from         hydrogen, deuterium, halogen, alkyl, cycloalkyl, heteroalkyl,         arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl,         heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl,         carboxylic acid, ester, nitrile, isonitrile, sulfanyl, sulfinyl,         sulfonyl, phosphino, and combinations thereof; and

wherein G³ and G⁵ are each independently a carbazole or a carbazole that is substituted with one or more groups selected from hydrogen, deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acid, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof.

According to another embodiment, a device comprising one or more organic light emitting devices is also provided. At least one of the one or more organic light emitting devices can include an anode, a cathode, and an organic layer, disposed between the anode and the cathode, wherein the organic layer can include a compound of Formula I, including all of the variations disclosed herein. The device can be a consumer product, an electronic component module, an organic light-emitting device, and/or a lighting panel.

According to yet another embodiment, a formulation containing the compound of Formula I, including all of the variations, is also provided.

Carbazole-containing compounds are known to be good hole-transporting, stable compounds in OLEDs, typically used in transport or host layers, but also as emitters. Use of the indolo[3,2,1-jk]carbazoles moiety in place of carbazole can impart unique properties with respect to stability, charge transport and sublimation temperature. The present disclosure provides a series of indolo[3,2,1-jk]carbazole-containing materials that are superior support materials in OLED devices, particularly when used as host and/or electron-blocking layer (EBL) materials.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an organic light emitting device.

FIG. 2 shows an inverted organic light emitting device that does not have a separate electron transport layer.

DETAILED DESCRIPTION

Generally, an OLED comprises at least one organic layer disposed between and electrically connected to an anode and a cathode. When a current is applied, the anode injects holes and the cathode injects electrons into the organic layer(s). The injected holes and electrons each migrate toward the oppositely charged electrode. When an electron and hole localize on the same molecule, an “exciton,” which is a localized electron-hole pair having an excited energy state, is formed. Light is emitted when the exciton relaxes via a photoemissive mechanism. In some cases, the exciton may be localized on an excimer or an exciplex. Non-radiative mechanisms, such as thermal relaxation, may also occur, but are generally considered undesirable.

The initial OLEDs used emissive molecules that emitted light from their singlet states (“fluorescence”) as disclosed, for example, in U.S. Pat. No. 4,769,292, which is incorporated by reference in its entirety. Fluorescent emission generally occurs in a time frame of less than 10 nanoseconds.

More recently, OLEDs having emissive materials that emit light from triplet states (“phosphorescence”) have been demonstrated. Baldo et al., “Highly Efficient Phosphorescent Emission from Organic Electroluminescent Devices,” Nature, vol. 395, 151-154, 1998; (“Baldo-I”) and Baldo et al., “Very high-efficiency green organic light-emitting devices based on electrophosphorescence,” Appl. Phys. Lett., vol. 75, No. 3, 4-6 (1999) (“Baldo-II”), which are incorporated by reference in their entireties. Phosphorescence is described in more detail in U.S. Pat. No. 7,279,704 at cols. 5-6, which are incorporated by reference.

FIG. 1 shows an organic light emitting device 100. The figures are not necessarily drawn to scale. Device 100 may include a substrate 110, an anode 115, a hole injection layer 120, a hole transport layer 125, an electron blocking layer 130, an emissive layer 135, a hole blocking layer 140, an electron transport layer 145, an electron injection layer 150, a protective layer 155, a cathode 160, and a barrier layer 170. Cathode 160 is a compound cathode having a first conductive layer 162 and a second conductive layer 164. Device 100 may be fabricated by depositing the layers described, in order. The properties and functions of these various layers, as well as example materials, are described in more detail in U.S. Pat. No. 7,279,704 at cols. 6-10, which are incorporated by reference.

More examples for each of these layers are available. For example, a flexible and transparent substrate-anode combination is disclosed in U.S. Pat. No. 5,844,363, which is incorporated by reference in its entirety. An example of a p-doped hole transport layer is m-MTDATA doped with F₄-TCNQ at a molar ratio of 50:1, as disclosed in U.S. Patent Application Publication No. 2003/0230980, which is incorporated by reference in its entirety. Examples of emissive and host materials are disclosed in U.S. Pat. No. 6,303,238 to Thompson et al., which is incorporated by reference in its entirety. An example of an n-doped electron transport layer is BPhen doped with Li at a molar ratio of 1:1, as disclosed in U.S. Patent Application Publication No. 2003/0230980, which is incorporated by reference in its entirety. U.S. Pat. Nos. 5,703,436 and 5,707,745, which are incorporated by reference in their entireties, disclose examples of cathodes including compound cathodes having a thin layer of metal such as Mg:Ag with an overlying transparent, electrically-conductive, sputter-deposited ITO layer. The theory and use of blocking layers is described in more detail in U.S. Pat. No. 6,097,147 and U.S. Patent Application Publication No. 2003/0230980, which are incorporated by reference in their entireties. Examples of injection layers are provided in U.S. Patent Application Publication No. 2004/0174116, which is incorporated by reference in its entirety. A description of protective layers may be found in U.S. Patent Application Publication No. 2004/0174116, which is incorporated by reference in its entirety.

FIG. 2 shows an inverted OLED 200. The device includes a substrate 210, a cathode 215, an emissive layer 220, a hole transport layer 225, and an anode 230. Device 200 may be fabricated by depositing the layers described, in order. Because the most common OLED configuration has a cathode disposed over the anode, and device 200 has cathode 215 disposed under anode 230, device 200 may be referred to as an “inverted” OLED. Materials similar to those described with respect to device 100 may be used in the corresponding layers of device 200. FIG. 2 provides one example of how some layers may be omitted from the structure of device 100.

The simple layered structure illustrated in FIGS. 1 and 2 is provided by way of non-limiting example, and it is understood that embodiments of the invention may be used in connection with a wide variety of other structures. The specific materials and structures described are exemplary in nature, and other materials and structures may be used. Functional OLEDs may be achieved by combining the various layers described in different ways, or layers may be omitted entirely, based on design, performance, and cost factors. Other layers not specifically described may also be included. Materials other than those specifically described may be used. Although many of the examples provided herein describe various layers as comprising a single material, it is understood that combinations of materials, such as a mixture of host and dopant, or more generally a mixture, may be used. Also, the layers may have various sublayers. The names given to the various layers herein are not intended to be strictly limiting. For example, in device 200, hole transport layer 225 transports holes and injects holes into emissive layer 220, and may be described as a hole transport layer or a hole injection layer. In one embodiment, an OLED may be described as having an “organic layer” disposed between a cathode and an anode. This organic layer may comprise a single layer, or may further comprise multiple layers of different organic materials as described, for example, with respect to FIGS. 1 and 2.

Structures and materials not specifically described may also be used, such as OLEDs comprised of polymeric materials (PLEDs) such as disclosed in U.S. Pat. No. 5,247,190 to Friend et al., which is incorporated by reference in its entirety. By way of further example, OLEDs having a single organic layer may be used. OLEDs may be stacked, for example as described in U.S. Pat. No. 5,707,745 to Forrest et al, which is incorporated by reference in its entirety. The OLED structure may deviate from the simple layered structure illustrated in FIGS. 1 and 2. For example, the substrate may include an angled reflective surface to improve out-coupling, such as a mesa structure as described in U.S. Pat. No. 6,091,195 to Forrest et al., and/or a pit structure as described in U.S. Pat. No. 5,834,893 to Bulovic et al., which are incorporated by reference in their entireties.

Unless otherwise specified, any of the layers of the various embodiments may be deposited by any suitable method. For the organic layers, preferred methods include thermal evaporation, ink-jet, such as described in U.S. Pat. Nos. 6,013,982 and 6,087,196, which are incorporated by reference in their entireties, organic vapor phase deposition (OVPD), such as described in U.S. Pat. No. 6,337,102 to Forrest et al., which is incorporated by reference in its entirety, and deposition by organic vapor jet printing (OVJP), such as described in U.S. Pat. No. 7,431,968, which is incorporated by reference in its entirety. Other suitable deposition methods include spin coating and other solution based processes. Solution based processes are preferably carried out in nitrogen or an inert atmosphere. For the other layers, preferred methods include thermal evaporation. Preferred patterning methods include deposition through a mask, cold welding such as described in U.S. Pat. Nos. 6,294,398 and 6,468,819, which are incorporated by reference in their entireties, and patterning associated with some of the deposition methods such as ink jet and OVJD. Other methods may also be used. The materials to be deposited may be modified to make them compatible with a particular deposition method. For example, substituents such as alkyl and aryl groups, branched or unbranched, and preferably containing at least 3 carbons, may be used in small molecules to enhance their ability to undergo solution processing. Substituents having 20 carbons or more may be used, and 3-20 carbons is a preferred range. Materials with asymmetric structures may have better solution processibility than those having symmetric structures, because asymmetric materials may have a lower tendency to recrystallize. Dendrimer substituents may be used to enhance the ability of small molecules to undergo solution processing.

Devices fabricated in accordance with embodiments of the present invention may further optionally comprise a barrier layer. One purpose of the barrier layer is to protect the electrodes and organic layers from damaging exposure to harmful species in the environment including moisture, vapor and/or gases, etc. The barrier layer may be deposited over, under or next to a substrate, an electrode, or over any other parts of a device including an edge. The barrier layer may comprise a single layer, or multiple layers. The barrier layer may be formed by various known chemical vapor deposition techniques and may include compositions having a single phase as well as compositions having multiple phases. Any suitable material or combination of materials may be used for the barrier layer. The barrier layer may incorporate an inorganic or an organic compound or both. The preferred barrier layer comprises a mixture of a polymeric material and a non-polymeric material as described in U.S. Pat. No. 7,968,146, PCT Pat. Application Nos. PCT/US2007/023098 and PCT/US2009/042829, which are herein incorporated by reference in their entireties. To be considered a “mixture”, the aforesaid polymeric and non-polymeric materials comprising the barrier layer should be deposited under the same reaction conditions and/or at the same time. The weight ratio of polymeric to non-polymeric material may be in the range of 95:5 to 5:95. The polymeric material and the non-polymeric material may be created from the same precursor material. In one example, the mixture of a polymeric material and a non-polymeric material consists essentially of polymeric silicon and inorganic silicon.

Devices fabricated in accordance with embodiments of the invention can be incorporated into a wide variety of electronic component modules (or units) that can be incorporated into a variety of electronic products or intermediate components. Examples of such electronic products or intermediate components include display screens, lighting devices such as discrete light source devices or lighting panels, etc. that can be utilized by the end-user product manufacturers. Such electronic component modules can optionally include the driving electronics and/or power source(s). Devices fabricated in accordance with embodiments of the invention can be incorporated into a wide variety of consumer products that have one or more of the electronic component modules (or units) incorporated therein. Such consumer products would include any kind of products that include one or more light source(s) and/or one or more of some type of visual displays. Some examples of such consumer products include flat panel displays, computer monitors, medical monitors, televisions, billboards, lights for interior or exterior illumination and/or signaling, heads-up displays, fully or partially transparent displays, flexible displays, laser printers, telephones, cell phones, tablets, phablets, personal digital assistants (PDAs), laptop computers, digital cameras, camcorders, viewfinders, micro-displays, 3-D displays, vehicles, a large area wall, theater or stadium screen, or a sign. Various control mechanisms may be used to control devices fabricated in accordance with the present invention, including passive matrix and active matrix. Many of the devices are intended for use in a temperature range comfortable to humans, such as 18 degrees C. to 30 degrees C., and more preferably at room temperature (20-25 degrees C.), but could be used outside this temperature range, for example, from −40 degree C. to +80 degree C.

The materials and structures described herein may have applications in devices other than OLEDs. For example, other optoelectronic devices such as organic solar cells and organic photodetectors may employ the materials and structures. More generally, organic devices, such as organic transistors, may employ the materials and structures.

The term “halo,” “halogen,” or “halide” as used herein includes fluorine, chlorine, bromine, and iodine.

The term “alkyl” as used herein contemplates both straight and branched chain alkyl radicals. Preferred alkyl groups are those containing from one to fifteen carbon atoms and includes methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, and the like. Additionally, the alkyl group may be optionally substituted.

The term “cycloalkyl” as used herein contemplates cyclic alkyl radicals. Preferred cycloalkyl groups are those containing 3 to 7 carbon atoms and includes cyclopropyl, cyclopentyl, cyclohexyl, and the like. Additionally, the cycloalkyl group may be optionally substituted.

The term “alkenyl” as used herein contemplates both straight and branched chain alkene radicals. Preferred alkenyl groups are those containing two to fifteen carbon atoms. Additionally, the alkenyl group may be optionally substituted.

The term “alkynyl” as used herein contemplates both straight and branched chain alkyne radicals. Preferred alkynyl groups are those containing two to fifteen carbon atoms. Additionally, the alkynyl group may be optionally substituted.

The terms “aralkyl” or “arylalkyl” as used herein are used interchangeably and contemplate an alkyl group that has as a substituent an aromatic group. Additionally, the aralkyl group may be optionally substituted.

The term “heterocyclic group” as used herein contemplates aromatic and non-aromatic cyclic radicals. Hetero-aromatic cyclic radicals also means heteroaryl. Preferred hetero-non-aromatic cyclic groups are those containing 3 or 7 ring atoms which includes at least one hetero atom, and includes cyclic amines such as morpholino, piperdino, pyrrolidino, and the like, and cyclic ethers, such as tetrahydrofuran, tetrahydropyran, and the like. Additionally, the heterocyclic group may be optionally substituted.

The term “aryl” or “aromatic group” as used herein contemplates single-ring groups and polycyclic ring systems. The polycyclic rings may have two or more rings in which two carbons are common to two adjoining rings (the rings are “fused”) wherein at least one of the rings is aromatic, e.g., the other rings can be cycloalkyls, cycloalkenyls, aryl, heterocycles, and/or heteroaryls. Additionally, the aryl group may be optionally substituted.

The term “heteroaryl” as used herein contemplates single-ring hetero-aromatic groups that may include from one to three heteroatoms, for example, pyrrole, furan, thiophene, imidazole, oxazole, thiazole, triazole, pyrazole, pyridine, pyrazine and pyrimidine, and the like. The term heteroaryl also includes polycyclic hetero-aromatic systems having two or more rings in which two atoms are common to two adjoining rings (the rings are “fused”) wherein at least one of the rings is a heteroaryl, e.g., the other rings can be cycloalkyls, cycloalkenyls, aryl, heterocycles, and/or heteroaryls. Additionally, the heteroaryl group may be optionally substituted.

The alkyl, cycloalkyl, alkenyl, alkynyl, aralkyl, heterocyclic group, aryl, and heteroaryl may be optionally substituted with one or more substituents selected from the group consisting of hydrogen, deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, cyclic amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acid, ether, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof.

As used herein, “substituted” indicates that a substituent other than H is bonded to the relevant position, such as carbon. Thus, for example, where R¹ is mono-substituted, then one R¹ must be other than H. Similarly, where R¹ is di-substituted, then two of R¹ must be other than H. Similarly, where R¹ is unsubstituted, R¹ is hydrogen for all available positions.

The “aza” designation in the fragments described herein, i.e. aza-dibenzofuran, aza-dibenzonethiophene, etc. means that one or more of the C—H groups in the respective fragment can be replaced by a nitrogen atom, for example, and without any limitation, azatriphenylene encompasses both dibenzo[f,h]quinoxaline and dibenzo[f,h]quinoline. One of ordinary skill in the art can readily envision other nitrogen analogs of the aza-derivatives described above, and all such analogs are intended to be encompassed by the terms as set forth herein.

It is to be understood that when a molecular fragment is described as being a substituent or otherwise attached to another moiety, its name may be written as if it were a fragment (e.g. phenyl, phenylene, naphthyl, dibenzofuryl) or as if it were the whole molecule (e.g. benzene, naphthalene, dibenzofuran). As used herein, these different ways of designating a substituent or attached fragment are considered to be equivalent.

According to an aspect of the present disclosure, a compound having a formula G¹-G²-G³-G⁴-G⁵, Formula I, disclosed. In Formula I, G¹ has the structure:

-   -   wherein R¹ and R³ each independently represent mono, di, tri, or         tetra substitutions, or no substitution,     -   wherein R² represents mono, di, or tri substitutions, or no         substitution,     -   wherein R¹, R², and R³ are each independently selected from the         group consisting of hydrogen, deuterium, halogen, alkyl,         cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino,         silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl,         heteroaryl, acyl, carbonyl, carboxylic acid, ester, nitrile,         isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and         combinations thereof;

wherein G² and G⁴ are each independently selected from the group consisting of a direct bond, an aryl group having from 6-30 carbon atoms, a heteroaryl group having from 3-30 carbon atoms, and combinations thereof,

-   -   wherein the aryl group and the heteroaryl group are optionally         further substituted with one or more groups selected from         hydrogen, deuterium, halogen, alkyl, cycloalkyl, heteroalkyl,         arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl,         heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl,         carboxylic acid, ester, nitrile, isonitrile, sulfanyl, sulfinyl,         sulfonyl, phosphino, and combinations thereof and

wherein G³ and G⁵ are each independently a carbazole or a carbazole that is substituted with one or more groups selected from hydrogen, deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acid, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof.

In one embodiment of the compound, G¹ connects to G² at the ring having R² substituent.

In another embodiment, G¹ connects to G² at the ring having R³ substituent.

In one embodiment, G² and G⁴ are each a direct bond.

In one embodiment, the compound of Formula I has a structure:

wherein R⁴ represents mono, di, tri, or tetra substitutions, or no substitution;

-   -   wherein R⁵ represents mono, di, or tri substitutions, or no         substitution;     -   wherein R⁴ and R⁵ are each independently selected from the group         consisting of hydrogen, deuterium, halogen, alkyl, cycloalkyl,         heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl,         cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl,         carbonyl, carboxylic acid, ester, nitrile, isonitrile, sulfanyl,         sulfinyl, sulfonyl, phosphino, and combinations thereof.

In another embodiment, the compound of Formula I has a structure:

-   -   wherein R⁶, and R⁷ each independently represents mono, di, tri,         or tetra substitutions, or no substitution;     -   wherein R⁶, and R⁷ are each independently selected from the         group consisting of hydrogen, deuterium, halogen, alkyl,         cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino,         silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl,         heteroaryl, acyl, carbonyl, carboxylic acid, ester, nitrile,         isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and         combinations thereof.

In another embodiment, the compound of Formula I has a structure selected from the group consisting of:

wherein R⁴ represents mono, di, or tri substitutions, or no substitution;

wherein R⁵ represents mono, di, tri, or tetra substitutions, or no substitution;

wherein R⁴, R⁵, and R⁸ are each independently selected from the group consisting of hydrogen, deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acid, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof.

In another embodiment, the compound of Formula I has a structure:

wherein R⁶, and R⁷ each independently represents mono, di, tri, or tetra substitutions, or no substitution;

wherein R⁶, R⁷, and R⁹ are each independently selected from the group consisting of hydrogen, deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acid, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof.

In some embodiments, the compound of Formula I has a structure selected from the group consisting of:

wherein R⁴, R⁶, and R⁷ each independently represents mono, di, tri, or tetra substitutions, or no substitution;

wherein R⁵ represents mono, di, or tri, substitutions, or no substitution;

wherein R⁴, R⁵, R⁶, R⁷, R⁸, and R⁹ are each independently selected from the group consisting of hydrogen, deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acid, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof.

In another embodiment of the compound of Formula I, G¹ is selected from the group consisting of:

In another embodiment of the compound of Formula I, the compound is selected from the group consisting of:

According to another aspect of the present disclosure, a device comprising one or more organic light emitting devices is disclosed. At least one of the one or more organic light emitting devices comprise: an anode; a cathode; and an organic layer, disposed between the anode and the cathode. In one embodiment, the organic layer comprises a compound having the formula G¹-G²-G³-G⁴-G⁵, Formula I;

wherein G¹ has the structure:

-   -   wherein R¹ and R³ each independently represent mono, di, tri, or         tetra substitution, or no substitution;     -   wherein R² represents mono, di, or tri substitution, or no         substitution;     -   wherein R¹, R², and R³ are each independently selected from the         group consisting of hydrogen, deuterium, halogen, alkyl,         cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino,         silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl,         heteroaryl, acyl, carbonyl, carboxylic acid, ester, nitrile,         isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and         combinations thereof;

wherein G² and G⁴ are each independently selected from the group consisting of a direct bond, an aryl group having from 6-30 carbon atoms, a heteroaryl group having from 3-30 carbon atoms, and combinations thereof; wherein the aryl group and the heteroaryl group are optionally further substituted with one or more groups selected from hydrogen, deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acid, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof; and

wherein G³ and G⁵ are each independently a carbazole or a carbazole that is substituted with one or more groups selected from hydrogen, deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acid, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof.

In one embodiment of the device, the organic layer is an emissive layer and the compound is a host.

In another embodiment, the organic layer further comprises a phosphorescent emissive dopant. The phosphorescent emissive dopant can be a transition metal complex having at least one ligand or part of the ligand, if the ligand is more than bidentate, selected from the group consisting of:

-   -   wherein R_(a), R_(b), R_(c), and R_(d) may represent mono, di,         tri, or tetra substitution, or no substitution;

wherein R_(a), R_(b), R_(c), and R_(d) are independently selected from the group consisting of hydrogen, deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof; and

wherein two adjacent substituents of R_(a), R_(b), R_(c), and R_(d) are optionally joined to form a fused ring or form a multidentate ligand.

In another embodiment of the device, the phosphorescent emissive dopant can be selected from the group consisting of:

In another embodiment of the device, the organic layer is an electron blocking layer and the compound having Formula I is an electron blocking material in the organic layer.

In another embodiment of the device, the organic layer is an electron transporting layer and the compound having Formula I is an electron transporting material in the organic layer.

In another embodiment, the device is selected from the group consisting of a consumer product, an electronic component module, an organic light-emitting device, and a lighting panel.

In yet another aspect of the present disclosure, a formulation that comprises a compound according to Formula I, and its variations as described herein, is described. The formulation can include one or more components selected from the group consisting of a solvent, a host, a hole injection material, hole transport material, and an electron transport layer material, disclosed herein.

Combination with Other Materials

The materials described herein as useful for a particular layer in an organic light emitting device may be used in combination with a wide variety of other materials present in the device. For example, emissive dopants disclosed herein may be used in conjunction with a wide variety of hosts, transport layers, blocking layers, injection layers, electrodes and other layers that may be present. The materials described or referred to below are non-limiting examples of materials that may be useful in combination with the compounds disclosed herein, and one of skill in the art can readily consult the literature to identify other materials that may be useful in combination.

HIL/HTL:

A hole injecting/transporting material to be used in the present invention is not particularly limited, and any compound may be used as long as the compound is typically used as a hole injecting/transporting material. Examples of the material include, but are not limited to: a phthalocyanine or porphyrin derivative; an aromatic amine derivative; an indolocarbazole derivative; a polymer containing fluorohydrocarbon; a polymer with conductivity dopants; a conducting polymer, such as PEDOT/PSS; a self-assembly monomer derived from compounds such as phosphonic acid and silane derivatives; a metal oxide derivative, such as MoO_(x); a p-type semiconducting organic compound, such as 1,4,5,8,9,12-Hexaazatriphenylenehexacarbonitrile; a metal complex, and a cross-linkable compound.

Examples of aromatic amine derivatives used in HIL or HTL include, but are not limited to the following general structures:

Each of Ar¹ to Ar⁹ is selected from the group consisting aromatic hydrocarbon cyclic compounds such as benzene, biphenyl, triphenyl, triphenylene, naphthalene, anthracene, phenalene, phenanthrene, fluorene, pyrene, chrysene, perylene, azulene; group consisting aromatic heterocyclic compounds such as dibenzothiophene, dibenzofuran, dibenzoselenophene, furan, thiophene, benzofuran, benzothiophene, benzoselenophene, carbazole, indolocarbazole, pyridylindole, pyrrolodipyridine, pyrazole, imidazole, triazole, oxazole, thiazole, oxadiazole, oxatriazole, dioxazole, thiadiazole, pyridine, pyridazine, pyrimidine, pyrazine, triazine, oxazine, oxathiazine, oxadiazine, indole, benzimidazole, indazole, indoxazine, benzoxazole, benzisoxazole, benzothiazole, quinoline, isoquinoline, cinnoline, quinazoline, quinoxaline, naphthyridine, phthalazine, pteridine, xanthene, acridine, phenazine, phenothiazine, phenoxazine, benzofuropyridine, furodipyridine, benzothienopyridine, thienodipyridine, benzoselenophenopyridine, and selenophenodipyridine; and group consisting 2 to 10 cyclic structural units which are groups of the same type or different types selected from the aromatic hydrocarbon cyclic group and the aromatic heterocyclic group and are bonded to each other directly or via at least one of oxygen atom, nitrogen atom, sulfur atom, silicon atom, phosphorus atom, boron atom, chain structural unit and the aliphatic cyclic group. Wherein each Ar is further substituted by a substituent selected from the group consisting of hydrogen, deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof.

In one aspect, Ar¹ to Ar⁹ is independently selected from the group consisting of:

wherein k is an integer from 1 to 20; X¹⁰¹ to X¹⁰⁸ is C (including CH) or N; Z¹⁰¹ is NAr¹, O, or S; Ar¹ has the same group defined above.

Examples of metal complexes used in HIL or HTL include, but not are limited to the following general formula:

wherein Met is a metal, which can have an atomic weight greater than 40; (Y¹⁰¹-Y¹⁰²) is a bidentate ligand, Y¹⁰¹ and Y¹⁰² are independently selected from C, N, O, P, and S; L¹⁰¹ is an ancillary ligand; k′ is an integer value from 1 to the maximum number of ligands that may be attached to the metal; and k′+k″ is the maximum number of ligands that may be attached to the metal.

In one aspect, (Y¹⁰¹-Y¹⁰²) is a 2-phenylpyridine derivative. In another aspect, (Y¹⁰¹-Y¹⁰²) is a carbene ligand. In another aspect, Met is selected from Ir, Pt, Os, and Zn. In a further aspect, the metal complex has a smallest oxidation potential in solution vs. Fc⁺/Fc couple less than about 0.6 V.

Host:

The light emitting layer of the organic EL device of the present invention preferably contains at least a metal complex as light emitting material, and may contain a host material using the metal complex as a dopant material. Examples of the host material are not particularly limited, and any metal complexes or organic compounds may be used as long as the triplet energy of the host is larger than that of the dopant. While the Table below categorizes host materials as preferred for devices that emit various colors, any host material may be used with any dopant so long as the triplet criteria is satisfied.

Examples of metal complexes used as host are preferred to have the following general formula:

wherein Met is a metal; (Y¹⁰³-Y¹⁰⁴) is a bidentate ligand, Y¹⁰³ and Y¹⁰⁴ are independently selected from C, N, O, P, and S; L¹⁰¹ is an another ligand; k′ is an integer value from 1 to the maximum number of ligands that may be attached to the metal; and k′+k″ is the maximum number of ligands that may be attached to the metal.

In one aspect, the metal complexes are:

wherein (O—N) is a bidentate ligand, having metal coordinated to atoms O and N.

In another aspect, Met is selected from Ir and Pt. In a further aspect, (Y¹⁰³-Y¹⁰⁴) is a carbene ligand.

Examples of organic compounds used as host are selected from the group consisting aromatic hydrocarbon cyclic compounds such as benzene, biphenyl, triphenyl, triphenylene, naphthalene, anthracene, phenalene, phenanthrene, fluorene, pyrene, chrysene, perylene, azulene; group consisting aromatic heterocyclic compounds such as dibenzothiophene, dibenzofuran, dibenzoselenophene, furan, thiophene, benzofuran, benzothiophene, benzoselenophene, carbazole, indolocarbazole, pyridylindole, pyrrolodipyridine, pyrazole, imidazole, triazole, oxazole, thiazole, oxadiazole, oxatriazole, dioxazole, thiadiazole, pyridine, pyridazine, pyrimidine, pyrazine, triazine, oxazine, oxathiazine, oxadiazine, indole, benzimidazole, indazole, indoxazine, benzoxazole, benzisoxazole, benzothiazole, quinoline, isoquinoline, cinnoline, quinazoline, quinoxaline, naphthyridine, phthalazine, pteridine, xanthene, acridine, phenazine, phenothiazine, phenoxazine, benzofuropyridine, furodipyridine, benzothienopyridine, thienodipyridine, benzoselenophenopyridine, and selenophenodipyridine; and group consisting 2 to 10 cyclic structural units which are groups of the same type or different types selected from the aromatic hydrocarbon cyclic group and the aromatic heterocyclic group and are bonded to each other directly or via at least one of oxygen atom, nitrogen atom, sulfur atom, silicon atom, phosphorus atom, boron atom, chain structural unit and the aliphatic cyclic group. Wherein each group is further substituted by a substituent selected from the group consisting of hydrogen, deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof.

In one aspect, host compound contains at least one of the following groups in the molecule:

wherein R¹⁰¹ to R¹⁰⁷ is independently selected from the group consisting of hydrogen, deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof, when it is aryl or heteroaryl, it has the similar definition as Ar's mentioned above. k is an integer from 0 to 20 or 1 to 20; k′ is an integer from 0 to 20. X¹⁰¹ to X¹⁰⁸ is selected from C (including CH) or N. Z¹⁰¹ and Z¹⁰² is selected from NR¹⁰¹, O, or S.

HBL:

A hole blocking layer (HBL) may be used to reduce the number of holes and/or excitons that leave the emissive layer. The presence of such a blocking layer in a device may result in substantially higher efficiencies as compared to a similar device lacking a blocking layer. Also, a blocking layer may be used to confine emission to a desired region of an OLED.

In one aspect, compound used in HBL contains the same molecule or the same functional groups used as host described above.

In another aspect, compound used in HBL contains at least one of the following groups in the molecule:

wherein k is an integer from 1 to 20; L¹⁰¹ is an another ligand, k′ is an integer from 1 to 3. ETL:

Electron transport layer (ETL) may include a material capable of transporting electrons. Electron transport layer may be intrinsic (undoped), or doped. Doping may be used to enhance conductivity. Examples of the ETL material are not particularly limited, and any metal complexes or organic compounds may be used as long as they are typically used to transport electrons.

In one aspect, compound used in ETL contains at least one of the following groups in the molecule:

wherein R¹⁰¹ is selected from the group consisting of hydrogen, deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof, when it is aryl or heteroaryl, it has the similar definition as Ar's mentioned above. Ar¹ to Ar³ has the similar definition as Ar's mentioned above. k is an integer from 1 to 20. X¹⁰¹ to X¹⁰⁸ is selected from C (including CH) or N.

In another aspect, the metal complexes used in ETL include, but are not limited to the following general formula:

wherein (O—N) or (N—N) is a bidentate ligand, having metal coordinated to atoms O, N or N, N; L¹⁰¹ is another ligand; k′ is an integer value from 1 to the maximum number of ligands that may be attached to the metal.

In any above-mentioned compounds used in each layer of the OLED device, the hydrogen atoms can be partially or fully deuterated. Thus, any specifically listed substituent, such as, without limitation, methyl, phenyl, pyridyl, etc. encompasses undeuterated, partially deuterated, and fully deuterated versions thereof. Similarly, classes of substituents such as, without limitation, alkyl, aryl, cycloalkyl, heteroaryl, etc. also encompass undeuterated, partially deuterated, and fully deuterated versions thereof.

In addition to and/or in combination with the materials disclosed herein, many hole injection materials, hole transporting materials, host materials, dopant materials, exciton/hole blocking layer materials, electron transporting and electron injecting materials may be used in an OLED. Non-limiting examples of the materials that may be used in an OLED in combination with materials disclosed herein are listed in Table A below. Table A lists non-limiting classes of materials, non-limiting examples of compounds for each class, and references that disclose the materials.

TABLE A MATERIAL EXAMPLES OF MATERIAL PUBLICATIONS Hole injection materials Phthalocyanine and porphryin compounds

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  and  

 

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Chem. Mater. 15, 3148 (2003) Metal carbene complexes

US20080018221 Phosphorescent OLED host materials Red hosts Arylcarbazoles

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Nature 395, 151 (1998)

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US20060280965

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US20090309488 US20090302743 US20100012931 Donor acceptor type molecules

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JP2008074939

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WO2005089025

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JP2007254297

JP2007254297 Indolocarbazoles

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J. Appl. Phys. 90, 5048 (2001)

WO2004107822 Tetraphenylene complexes

US20050112407 Metal phenoxypyridine compounds

WO2005030900 Metal coordination complexes (e.g., Zn, Al with N{circumflex over ( )}N ligands)

US20040137268, US20040137267 Blue hosts Arylcarbazoles

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WO2006114966, US20090167162

US20090167162

WO2009086028

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US20050238919

WO2009003898 Silicon/Germanium aryl compounds

EP2034538A Aryl benzoyl ester

WO2006100298 Carbazole linked by non-conjugated groups

US20040115476 Aza-carbazoles

US20060121308 High triplet metal organometallic complex

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Appl. Phys. Lett. 78, 1622 (2001)

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SYNTHESIS OF COMPOUNDS

Synthesis of 9-(2-bromophenyl)-9H-carbazole/9-(2-iodophenyl)-9H-carbazole Mixture

9H-carbazole (9.8 g, 58.9 mmol) and 1-bromo-2-iodobenzene (50 g, 177 mmol) were mixed with copper (0.94 g, 14.7 mmol) and potassium carbonate (16.3 g, 118 mmol) and the slurry was heated to 200° C. for 12 hours. After cooling to room temperature, the reaction was filtered through celite, washing with DCM. The DCM was removed under reduced pressure and the excess 1-bromo-2-iodobenzene was removed by Kugelrohr distillation. The residue was then chromatographed on silica with 0-3% DCM in hetane and recrystallized from heptane to yield 14.4 g of a mixture of 9-(2-bromophenyl)-9H-carbazole (˜60%) and 9-(2-iodophenyl)-9H-carbazole (˜40%).

Synthesis of 9-(2-bromo-5-chlorophenyl)-9H-carbazole

2-bromo-5-chloroaniline (7.9 g, 38.4 mmol), 2,2′-diiodo-1,1′-biphenyl (13.0 g, 32.0 mmol), Pd₂(dba)₃ (0.59 g, 0.64 mmol) and tricyclohexylphosphine (0.72 g, 2.6 mmol) were added to toluene (250 mL) followed by sodium tert-butoxide (9.2 g, 96 mmol). The mixture was degassed thoroughly before being heated to reflux for 4 hours. The crude reaction mixture was cooled and filtered through a celite plug, washing with toluene and DCM. The filtrate was rotovapped to give 14.7 g of a dark oil, which was chromatographed on silica gel with 99/1 heptane/DCM to 90/10 heptane DCM to give 9.5 g (83%) of 9-(2-bromo-5-chlorophenyl)-9H-carbazole, which was used without further purification.

Synthesis of indolo[3,2,1-jk]carbazole

A mixture of 9-(2-bromophenyl)-9H-carbazole (˜60%) and 9-(2-iodophenyl)-9H-carbazole (˜40%) (14.4 g, ˜42 mmol), palladium(II) acetate (1.4 g, 6.3 mmol), triphenylphosphine (3.9 g, 14.7 mmol), N-benzyl-N,N-diethylethanaminium chloride (9.6 g, 42.0 mmol), and potassium carbonate (29.0 g, 210 mmol) were mixed with 300 mL DMA and the mixture was degassed before being heated to reflux for 4 hours. After cooling to room temperature, the reaction was filtered through a plug of celite and washed with DCM. The crude material was then chromatographed on silica with 0-1% DCM in heptane and recrystallized from cold heptane to yield 8.5 g (84%) of indolo[3,2,1-jk]carbazole.

Synthesis of 5-nitroindolo[3,2,1-jk]carbazole

9H-carbazole (10.0 g, 59.8 mmol), 2-chloro-1-fluoro-4-nitrobenzene (10.5 g, 59.8 mmol) and potassium carbonate (24.8 g, 179 mmol) were added to dimethylacetamide (100 mL) and the mixture heated to 160° C. (bath temp.) for 16 hours. The reaction was cooled to room temperature and palladium(II) acetate (0.67 g, 3.0 mmol) and PCy₃-HBF₄ (2.2 g, 6.0 mmol) were added. The reaction mixture was reheated to reflux for 16 hours. The reaction was cooled to room temperature and DCM and 10% LiCl (aq.) were added. After separation, the aqueous was washed twice more with DCM and combined with organics twice with 10% LiCl (aq.), dried over sodium sulfate and rotovapped (with rotary evaporator) to give 31.1 g of a dark solid. The solid was lixiviated with DCM and filtered to give 7.4 g of an orange solid (pure product by GC/MS and TLC). The filtrate was stripped to give 14 g of a dark solid that was chromatographed on silica with DCM to give 5.6 g of a yellow-orange solid. This solid was lixiviated with heptane and MeOH to give 5.1 g of an orange solid. The solids were combined to give 13.5 g (79%) of 5-nitroindolo[3,2,1-jk]carbazole.

Synthesis of 6-chloroindolo[3,2,1-jk]carbazole

9-(2-bromo-5-chlorophenyl)-9H-carbazole (9.5 g, 26.6 mmol), palladium(II) acetate (0.90 g, 4.0 mmol), triphenylphosphine (2.4 g, 9.3 mmol), N-benzyl-N,N-diethylethanaminium chloride (6.1 g, 26.6 mmol), and potassium acetate (7.8 g, 80 mmol) were mixed with DMAc (200 mL) and the mixture was degassed before being heated to reflux for 4 hours. After cooling, the reaction mixture was passed through celite and washed with EtOAc and DCM. After removing the solvents under reduced pressure, 11.1 g of a dark yellow solid was obtained. This material was chromatographed on silica gel with 99/1 heptane/DCM to 90/10 heptane/DCM to give 6.7 g of a white solid. This material was recrystallized from DCM/heptane to give 4.4 g (71%) of 6-chloroindolo[3,2,1-jk]carbazole as white needles.

Synthesis of bromoindolo[3,2,1-jk]carbazole

To 9.0 g of indolo[3,2,1-jk]carbazole (37.3 mmol) in 100 mL of DMF at 0° C., NBS (6.6 g, 37.3 mmol) in 50 mL DMF was added dropwise. The reaction was allowed to warm to room temperature over 16 hours and 100 mL of sodium metabisulfite solution was added to the reaction. After stirring for 20 min., the solid was filtered and washed with water and ethanol. The filtrate was extracted 3×100 mL with ethyl acetate and dried over sodium sulfate. After removal of the solvent, the residue was combined with the filtered solid and chromatographed on silica gel with 0-3% DCM in heptane to yield 10 g (84%) of a mixture of 60% 2-bromoindolo[3,2,1-jk]carbazole and 40% 5-bromoindolo[3,2,1-jk]carbazole. The mixture was carried to the next step without further purification.

Synthesis of (4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)indolo[3,2,1-jk]carbazole

A mixture of 60% 2-bromoindolo[3,2,1-jk]carbazole and 40% 5-bromoindolo[3,2,1-jk]carbazole (10 g, 21.9 mmol), 4,4,4′,4′,5,5,5′,5′-octamethyl-2,2′-bi(1,3,2-dioxaborolane) (16.7 g, 65.6 mmol), Pd₂(dba)₃ (0.60 g, 0.66 mmol), dppf (0.73 g, 1.3 mmol) and potassium acetate (6.4 g, 65.6 mmol) in 200 mL dioxane was bubbled with nitrogen for 20 min. and the reaction was allowed to reflux for 16 hours. After cooling to room temperature, the reaction was filtered through a plug of celite and washed with DCM. The solvent evaporated and excess (Bpin)₂ was removed by Kugelrohr distillation. The residue was chromatographed on silica with 20-50% DCM in heptane. The product was recrystallized from heptane to yield 4.3 g of 2-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)indolo[3,2,1-jk]carbazole (54%; 31% over 2 steps). 5-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)indolo[3,2,1-jk]carbazole eluted after the desired product.

Synthesis of indolo[3,2,1-jk]carbazol-2-ol

Hydrogen peroxide (4.6 mL, 44.9 mmol) was added to 2-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)indolo[3,2,1-jk]carbazole (3.3 g, 9.0 mmol) in 20 mL of ethanol and the reaction was allowed to stir at room temperature for 16 hours. Hydrogen peroxide (4.6 mL, 44.9 mmol) was added once more and the reaction was stirred for 16 hours, filtered and washed with ethanol to yield 1.5 g (65%) of indolo[3,2,1-jk]carbazol-2-ol as a white solid. The product was confirmed by NMR and GC/MS.

Synthesis of indolo[3,2,1-jk]carbazol-2-yl trifluoromethanesulfonate

To indolo[3,2,1-jk]carbazol-2-ol (1.5 g, 5.8 mmol) and pyridine (0.94 mL, 11.67 mmol) in 30 mL of DCM at 0° C., trifluoromethanesulfonic anhydride (1.97 mL, 11.66 mmol) was added dropwise. After completion of the addition, the reaction was allowed to warm up to room temperature for 16 hours and quenched with 50 mL of aqueous potassium carbonate solution. The aqueous was extracted 3×50 mL with DCM and combined organics washed with sodium carbonate and dried over sodium sulfate. After evaporation, the crude product was passed through a plug of silica gel, eluting with DCM. Evaporation of the eluent gave 2.1 g (90%) of indolo[3,2,1-jk]carbazol-2-yl trifluoromethanesulfonate as a white solid. The product was confirmed by NMR.

Synthesis of indolo[3,2,1-jk]carbazol-5-amine

5-nitroindolo[3,2,1-jk]carbazole (12.4 g, 43.3 mmol) was added to acetic acid (100 mL) and 2-propanol (100 mL). Ammonium chloride (0.46 g, 8.7 mmol) was dissolved in water (10 mL) and added to the reaction mixture. Iron (9.7 g, 173 mmol) was added slowly in 4×2 g portions and then heated slowly to 90° C. for 6 hours. The reaction mixture was then cooled to room temperature and filtered through a celite/silica plug and washed with toluene and DCM. After evaporation of the solvent, the crude material was adsorbed on celite and chromaotgraphed on silica with DCM to 9/1 DCM/EtOAc. The resulting product was lixiviated with MeOH to give 6.7 g (60%) of indolo[3,2,1-jk]carbazol-5-amine as an orange solid.

Synthesis of 5-iodoindolo[3,2,1-jk]carbazole

In a 1000 mL 2-neck flask with mechanical stirring, indolo[3,2,1-jk]carbazol-5-amine (6.7 g, 26.1 mmol) and p-toluenesulfonic acid monohydrate (24.9 g, 131 mmol) were added to t-BuOH (200 mL) and water (30 mL) and cooled to 10° C. Sodium nitrite (5.4 g, 78 mmol) and potassium iodide (17.4 g, 105 mmol) were dissolved in water (50 mL) and added dropwise to the reaction mixture, causing immediate darkening and thickening of the reaction mixture, which was warmed to room temperature and stirred for 16 hours. Water and MeOH were added followed by solid sodium bicarbonate (10.98 g, 131 mmol) and then a saturated bicarbonate solution until the pH was 10-11. Solid sodium thiosulfate (12.40 g, 78 mmol) was added and the color lightened considerably. The solid was filtered and washed with water and a little MeOH to give a dark orange solid. The filtrate was washed 3× with DCM and the combined organics with water and brine. This was combined with the solid above and the solvent removed. The crude product was chromatographed on silica gel with 5-7% DCM in heptane and crystalized from DCM to yield 3.7 g (39%) of 5-iodoindolo[3,2,1-jk]carbazole.

Synthesis of Compound 2

Indolo[3,2,1-jk]carbazol-2-yl trifluoromethanesulfonate (2.0 g, 5.1 mmol), 9-phenyl-9H,9′H-3,3′-bicarbazole (2.3 g, 5.6 mmol), Pd₂(dba)₃ (0.094 g, 0.10 mmol) and dicyclohexyl(2′,6′-dimethoxy-[1,1′-biphenyl]-2-yl)phosphine (0.17 g, 0.41 mmol) were added to m-xylene (50 mL). Sodium tert-butoxide (0.99 g, 10.3 mmol) was then added and the mixture was thoroughly degassed before being heated to reflux for 16 hours. After cooling to room temperature, the reaction filtered, washing with toluene. The filtrate was reduced and chromatographed on silica gel with 10-20% DCM in heptane and further recrystallized from heptane to give 0.65 g (20%) of Compound 2 as a white solid.

Synthesis of Compound 14

9-phenyl-9H,9′H-3,3′-bicarbazole (3.1 g, 7.6 mmol), 5-iodoindolo[3,2,1-jk]carbazole (2.8 g, 7.6 mmol), Pd₂(dba)₃ (0.14 g, 0.15 mmol), dicyclohexyl(2′,6′-dimethoxy-[1,1′-biphenyl]-2-yl)phosphine (0.25 g, 0.61 mmol) and sodium tert-butoxide (2.2 g, 22.9 mmol) were added to m-xylene (75 mL) and the mixture thoroughly degassed before being heated to reflux for 16 hours. The crude reaction mixture was filtered through celite and washed with DCM. The filtrate was rotovapped to give 9.0 g of a dark solid. The crude material was chromatorgraphed on silica gel with 8/2 heptane/DCM to 1/1 heptane/DCM. The product fractions were recrystallized form DCM/MeOH to yield 3.8 g (77%) of Compound 14 as a white solid. The product was confirmed by NMR and LC/MS.

Synthesis of Compound 13

9H-3,9′-bicarbazole (4.2 g, 12.7 mmol), 5-iodoindolo[3,2,1-jk]carbazole (3.9 g, 10.6 mmol), Pd₂(dba)₃ (0.20 g, 0.21 mmol), dicyclohexyl(2′,6′-dimethoxy-[1,1′-biphenyl]-2-yl)phosphine (0.35 g, 0.85 mmol) and sodium tert-butoxide (3.1 g, 31.9 mmol) were added to m-xylene (100 mL) and the mixture thoroughly degassed before being heated to reflux for 16 hours. The crude reaction mixture was cooled and filtered through celite and washed with DCM and hot toluene. The filtrate was reduced and the crude material was chromatographed on silica gel with 9/1 heptane/DCM to 7/3 heptane/DCM to give 5.5 g (91%) of a Compound 13 as white solid.

Synthesis of Compound 26

9-phenyl-9H,9′H-3,3′-bicarbazole (5.3 g, 13.1 mmol), 6-chloroindolo[3,2,1-jk]carbazole (3.0 g, 10.9 mmol), Pd₂(dba)₃ (0.20 g, 0.22 mmol), dicyclohexyl(2′,6′-dimethoxy-[1,1′-biphenyl]-2-yl)phosphine (0.36 g, 0.87 mmol) and sodium tert-butoxide (3.1 g, 32.6 mmol) were added to m-xylene (80 mL) and the mixture thoroughly degassed before being heated to reflux for 16 hours. After cooling the reaction mixture was filtered and washed with DCM and EtOAc. The filtered solid was boiled in hot toluene and filtered through a plug of silica while still warm and eluted with more hot toluene. The filtrate was reduced to give 7.4 g of an off-white solid, which was recrystallized from toluene to give 5.7 g of Compound 26 as a bright white solid. The product was confirmed by NMR and LC/MS.

EXPERIMENTAL

All OLED devices were fabricated by high vacuum (˜10⁻⁷ Torr) thermal evaporation. The anode electrode was 120 nm of indium tin oxide (ITO). The cathode electrode consisted of 1 nm of LiF followed by 100 nm of Al. All devices were encapsulated with a glass lid sealed with an epoxy resin in a nitrogen glove box (<1 ppm of H₂O and O₂) immediately after fabrication, and a moisture getter was incorporated inside the package.

Device 1a.

This device has organic stacks consisting of, sequentially, from the ITO surface, 10 nm of LG101 (from LG Chem) as the hole injection layer (HIL), 40 nm of Compound HTM as the hole-transport layer (HTL), 5 nm of Compound 26 as an electron-blocking layer (EBL), 30 nm of Compound HA doped with 12% of Compound GD as the emissive layer (EML). On top of the EML, 5 nm of Compound HA was deposited as the hole blocking layer (HBL), followed by 45 nm of tris(8-hydroxyquinolinato)aluminum (Alq₃) as the electron-transport layer (ETL). The structures of the compounds used are shown below.

Device 1b.

Device 1b has the same structure as that of Device 1a except that Compound 14 was used as the EBL.

Device 1c.

Device 1c has the same structure as that of Device 1a except that Compound HB was used as the EBL.

Device 1d.

Device 1d has the same structure as that of Device 1a except that Compound HD was used as the EBL.

The results of Devices 1a-1d are shown in Table 1 below:

TABLE 1 Luminous Efficacy Device EBL at 1000 nits (cd/A) Device 1a Compound 26 70.1 (inventive) Device 1b Compound 14 71.9 (inventive) Device 1c Compound HB 54.8 (comparative) Device 1d Compound HD 67.1 (comparative)

As can be seen from Table 1, the luminous efficacy of the inventive compounds are high at 70.1 cd/A for Compound 26 and 71.9 cd/A for Compound 14. This is especially striking when compared to the comparative devices using Compound HB (54.8 cd/A) and Compound HD (67.1 cd/A). The data shows that the electronic structure of the inventive compounds is better disposed to serve as an electron blocking layer relative to the comparative examples. However, this not obvious from looking at the chemical structures of the compounds.

Device 2a.

A second set of device has organic stacks consisting of, sequentially, from the ITO surface, 10 nm of LG101 (from LG Chem) as the hole injection layer (HIL), 40 nm of Compound HTM as the hole-transport layer (HTL), and 30 nm of emissive layer (EML). On top of the EML, 5 nm of Compound HC was deposited as the hole blocking layer (HBL), followed by 45 nm of tris(8-hydroxyquinolinato)aluminum (Alq₃) as the electron-transport layer (ETL). The EML consists of three components: 70 wt % of Compound 26 is used as the host, with 20 wt % of Compound HC as co-host, and 10 wt % of Compound GD as emissive dopant.

Device 2b.

Device 2b has the same structure as that of Device 2a except that Compound 13 was used as the host instead of Compound 26.

Device 2c.

Device 2c has the same structure as that of Device 2a except that Compound HD was used as the host instead of Compound 26.

The results for Devices 2a, 2b, and 2c are shown in Table 2 below:

TABLE 2 EML Compounds Luminous Efficacy Device Host Co-host Dopant at 1000 nits (cd/A) Device 2a Compound 26 HC GD 65.4 (inventive) Device 2b Compound 13 HC GD 74.6 (inventive) Device 2c Compound HD HC GD 61.8 (comparative)

As can be seen from Table 2, the luminous efficacy of the inventive compounds, when used as hosts along with co-host HC are high at 65.4 cd/A for Compound 26 and 74.6 cd/A for Compound 13. This is especially striking when compared to the comparative device using Compound HD (61.8 cd/A) as a host. Again, the inventive compounds described herein show a remarkable ability to act as hole-transporting hosts when used in combination with an electron-transporting host (HC), which is not apparent from the chemical structure alone when compared to the comparative examples. 

We claim:
 1. A compound having a structure according to a formula G¹-G²-G³-G⁴-G⁵, Formula I; wherein G¹ has the structure:

wherein R¹ and R³ each independently represent mono, di, tri, or tetra substitutions, or no substitution, wherein R² represents mono, di, or tri substitutions, or no substitution, wherein R¹, R², and R³ are each independently selected from the group consisting of hydrogen, deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acid, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof; wherein G² and G⁴ are each independently selected from the group consisting of a direct bond, an aryl group having from 6-30 carbon atoms, a heteroaryl group having from 3-30 carbon atoms, and combinations thereof, wherein the aryl group and the heteroaryl group are optionally further substituted with one or more groups selected from hydrogen, deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acid, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof; wherein G³ and G⁵ are each independently a carbazole or a carbazole that is substituted with one or more groups selected from hydrogen, deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acid, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof; and wherein the structure according to Formula I is further defined according to at least one of:

wherein R⁶, and R⁷ each independently represents mono, di, tri, or tetra substitutions, or no substitution; wherein R⁶, and R⁷ are each independently selected from the group consisting of hydrogen, deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acid, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof;

wherein R⁴ represents mono, di, or tri substitutions, or no substitution; wherein R⁵ represents mono, di, tri, or tetra substitutions, or no substitution; wherein R⁴, R⁵, and R⁸ are each independently selected from the group consisting of hydrogen, deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acid, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof; and

wherein R⁴ represents mono, di, or tri substitutions, or no substitution; wherein R⁵ represents mono, di, tri, or tetra substitutions, or no substitution; wherein R⁴, R⁵, and R⁸ are each independently selected from the group consisting of hydrogen, deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acid, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof.
 2. The compound of claim 1, wherein G¹ connects to G² at the ring having R² substituent.
 3. The compound of claim 1, wherein G¹ connects to G² at the ring having R³ substituent.
 4. The compound of claim 1, wherein G² and G⁴ are each a direct bond.
 5. The compound of claim 1, wherein the compound has a structure selected from the group consisting of:

wherein R⁴, R⁶, and R⁷ each independently represents mono, di, tri, or tetra substitutions, or no substitution; wherein R⁵ represents mono, di, or tri, substitutions, or no substitution; wherein R⁴, R⁵, R⁶, R⁷, R⁸, and R⁹ are each independently selected from the group consisting of hydrogen, deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acid, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof.
 6. The compound of claim 1, wherein G¹ is selected from the group consisting of:


7. The compound of claim 1, wherein the compound is selected from the group consisting of:


8. A formulation comprising the compound in claim
 1. 9. A device comprising one or more organic light emitting devices, at least one of the organic light emitting devices comprising: an anode; a cathode; and an organic layer, disposed between the anode and the cathode, comprising a compound having a structure according to the formula G¹-G²-G³-G⁴-G⁵, Formula I; wherein G¹ has the structure:

wherein R¹ and R³ each independently represent mono, di, tri, or tetra substitution, or no substitution; wherein R² represents mono, di, or tri substitution, or no substitution; wherein R¹, R², and R³ are each independently selected from the group consisting of hydrogen, deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acid, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof; wherein G² and G⁴ are each independently selected from the group consisting of a direct bond, an aryl group having from 6-30 carbon atoms, a heteroaryl group having from 3-30 carbon atoms, and combinations thereof; wherein the aryl group and the heteroaryl group are optionally further substituted with one or more groups selected from hydrogen, deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acid, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof; wherein G³ and G⁵ are each independently a carbazole or a carbazole that is substituted with one or more groups selected from hydrogen, deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acid, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof; and wherein the organic layer is an electron transporting layer and the compound having Formula I is an electron transporting material in the organic layer.
 10. The device of claim 9, wherein the device is selected from the group consisting of a consumer product, an electronic component module, an organic light-emitting device, and a lighting panel.
 11. The device of claim 9, wherein the organic layer further comprises a phosphorescent emissive dopant.
 12. The device of claim 11, wherein the phosphorescent emissive dopant is a transition metal complex having at least one ligand or part of the ligand, if the ligand is more than bidentate, selected from the group consisting of:

wherein R_(a), R_(b), R_(c), and R_(d) may represent mono, di, tri, or tetra substitution, or no substitution; wherein R_(a), R_(b), R_(c), and R_(d) are independently selected from the group consisting of hydrogen, deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof; and wherein two adjacent substituents of R_(a), R_(b), R_(c), and R_(d) are optionally joined to form a fused ring or form a multidentate ligand.
 13. The device of claim 12, wherein the phosphorescent emissive dopant is selected from the group consisting of:


14. A device comprising one or more organic light emitting devices, at least one of the organic light emitting devices comprising: an anode; a cathode; and an organic layer, disposed between the anode and the cathode, comprising a compound having a structure according to the formula G¹-G²-G³-G⁴-G⁵, Formula I; wherein G¹ has the structure:

wherein R¹ and R³ each independently represent mono, di, tri, or tetra substitution, or no substitution; wherein R² represents mono, di, or tri substitution, or no substitution; wherein R¹, R², and R³ are each independently selected from the group consisting of hydrogen, deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acid, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof; wherein G² and G⁴ are each independently selected from the group consisting of a direct bond, an aryl group having from 6-30 carbon atoms, a heteroaryl group having from 3-30 carbon atoms, and combinations thereof; wherein the aryl group and the heteroaryl group are optionally further substituted with one or more groups selected from hydrogen, deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acid, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof; wherein G³ and G⁵ are each independently a carbazole or a carbazole that is substituted with one or more groups selected from hydrogen, deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acid, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof; and wherein the structure according to Formula I, is further defined according to at least one of:

wherein R⁶, and R⁷ each independently represents mono, di, tri, or tetra substitutions, or no substitution; wherein R⁶, and R⁷ are each independently selected from the group consisting of hydrogen, deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acid, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof; or

wherein R⁴ represents mono, di, or tri substitutions, or no substitution; wherein R⁵ represents mono, di, tri, or tetra substitutions, or no substitution; wherein R⁴, R⁵, and R⁸ are each independently selected from the group consisting of hydrogen, deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acid, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof; and

wherein R⁴ represents mono, di, or tri substitutions, or no substitution; wherein R⁵ represents mono, di, tri, or tetra substitutions, or no substitution; wherein R⁴, R⁵, and R⁸ are each independently selected from the group consisting of hydrogen, deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acid, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof.
 15. The device of claim 14, wherein the organic layer is an emissive layer and the compound is a host.
 16. The device of claim 14, wherein the organic layer is an electron blocking layer and the compound having Formula I is an electron blocking material in the organic layer.
 17. The device of claim 14, wherein the organic layer further comprises a phosphorescent emissive dopant.
 18. The device of claim 14, wherein the device is selected from the group consisting of a consumer product, an electronic component module, an organic light-emitting device, and a lighting panel. 